深圳求水山隧道下穿机荷高速公路收费站，地面车流量大，隧道超浅埋并穿越回填土富水地层，结构松软，施工沉降难以控制，施工不当会引起隧道变形坍塌和路面沉陷，危及地面行车安全。为找出控制沉降的关键步序，运用FLAC3D软件对施工过程进行沉降分析，先确定超浅埋隧道在下穿富水软土地层条件下产生变形的原因，再对隧道施工各工序的时间和步距数据进行调研与分析。提出优化后隧道施工工法（双侧壁导坑微台阶工法）及拱脚加固、掌子面封闭、地下水处治、开挖及支护工序卡控、监控量测等控制变形技术措施，成功解决变形沉降难题，将拱顶下沉控制在45.6 mm左右，地面沉降控制在184 mm左右，化解了工程安全风险，确保了隧道施工和地面行车安全。

The Qiushuishan tunnel, super shallow buried, crosses underneath toll station of Shenzhen Bao’an International AirportHeao Highway in Shenzhen in waterrich backfill soil. The traffic on the ground is heavy and the construction deformation is difficult. The ground settlement during tunnel construction is analyzed by software FLAC3D. And then the ground deformation causes are determined and the time of each construction phase and bench data are studied and analyzed. Finally, a series of technologies, i.e. doubleside drift and micro bench method, arch feet reinforcement, working face closure, groundwater treatment, control of excavation and support process and monitoring, are adopted. The crown top settlement is controlled within 45.6 mm and ground surface settlement is controlled within 184 mm, which have guaranteed the safety of the tunnel and vehicle on the ground.